LOS ANGELES (CBSLA.com) — The head of LA County’s child protective services agency has announced he will retire at the end of January.

Philip Browning, who for five years has overseen the largest such child welfare system in the country, told staffers Wednesday he will resign as director of the Los Angeles County Department of Children and Family Services (DCFS). His last day will be Jan. 31, 2017.

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The announcement came as a surprise to some staffers, according to the Chronicle of Social Change. The agency has some 8,800 workers, including 4,000 children’s social workers overseeing the cases of about 40,000 children, the Chronicle reports.

Browning was hired by the LA County Board of Supervisors to lead DCFS in 2011 after the agency had cycled through two previous directors in less than a year.

In his memo to staff Wednesday, Browning touted achievements such as bringing new technologies into the agency and reducing caseloads for employees by hiring more social workers, the Los Angeles Times reported.

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Browning also faced sharp criticism following high-profile deaths of abused children, including 8-year-old Gabriel Fernandez and 11-year-old Yonatan Aguilar. Both cases raised questions of why DCFS had failed to intervene on those children’s’ behalf.

Those deaths also ushered in reforms: Fernandez’s death was followed by the creation of the county’s Office of Child Protection, and Aguilar’s death led county supervisors to call for a review of how the risk of child abuse is calculated in the county.

Browning during his tenure oversaw the creation and eventual closure of transitional shelters for abused children, the Chronicle reported.

The Los Angeles County Board of Supervisors will pick Browning’s successor.

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